At present, the shaft guide devices associated to the hoisting containers of hoists in the coal mines in China mainly include rigid assembled shaft guides and steel-wire-rope guides. As deep mining in coal mines is developed, rigid assembled shaft guides have been replaced by steel-wire-rope guides, owing to their drawbacks such as high capital investment, difficulties in construction, and difficulties in maintenance and repair after deformation, etc. Since steel wire ropes belong to a flexible material, the wide application of steel-rope guides inevitably brings a problem of shaft guide rope tensioning. Well-known tensioning methods that can effectively provide tensioning force for shaft guide ropes mainly include counterweight tensioning method and hydraulic tensioning method.
Regarding the counterweight tensioning method, usually a counterweight is mounted on the lower part of the shaft guide rope, so as utilize the gravity of the counterweight to provide tensioning force for the shaft guide rope; though the tensioning force is stable, the size of the counterweight has to be increased as the tensioning force is increased; consequently, a large water pocket has to be excavated in the shaft bottom to accommodate the counterweight; in addition, the counterweight may fall into the water pocket in the shaft bottom; once such a problem occurs, it is difficult to repair, and the production may be delayed; regarding the hydraulic tensioning method, usually a hydraulic cylinder is arranged on the shaft-head frame, a lifting rope clamp devices are used to provide tensioning force for the steel wire rope. Though the tensioning force on the shaft guide rope can be adjusted well with that method, the hydraulic cylinder arranged at the shaft head has to bear the weight of the steel wire rope having a length of thousands of meters while providing increasing tensioning force as the mining depth is increased; consequently, the cost will be increased vehemently; in addition, it is difficult to arrange the hydraulic station, owing to the large size of the hydraulic station.
It can be seen from the above analysis that the existing tensioners cannot meet the requirement at present and in the future.